Modern multifunctional map displays, particularly those used in vehicles, such as aircraft, watercraft, or spacecraft, are capable of displaying a considerable amount of information such as vehicle position, attitude, navigation, target, and terrain information. Most modern displays additionally allow a vehicle flight plan to be displayed from different views, either a lateral view, a vertical view, or perspective views which can be displayed individually or simultaneously on the same display. The lateral view, generally known as a lateral map display, is basically a top-view of the aircraft flight plan, and may include, for example, a top-view aircraft symbol, waypoint symbols, line segments that interconnect the waypoint symbols, and range rings. The lateral map may also include various map features including, for example, weather information, terrain information, political boundaries, and navigation aids. The terrain information may include situational awareness (SA) terrain, as well as terrain cautions and warnings which, among other things, may indicate where the aircraft may potentially impact terrain.
The perspective view provides a three-dimensional view of the vehicle flight plan. The perspective view display may include one or more of the above-mentioned features that are displayed on the lateral map, including the terrain information. Although the present method of displaying terrain data in the perspective view display is effective, it does suffer certain drawbacks. For example, in some instances, the display may not provide sufficient information for a vehicle operator to determine a distance between the vehicle and a point or an object on the terrain. Consequently, the object may mistakenly appear to be close to or far away from the aircraft In other instances, a three-dimensional translucent plane having a fixed range with respect to a current position of the vehicle is laid on top of terrain and into a flight space. In these cases, the planes intrude into the visual space of the display, are always shown in the display, and may obstruct the operator's view of other information on the same display.
Hence, there is a need for a display system and method that addresses one or more of the above-noted drawbacks. Namely, there is a need for a display system and method that accurately displays distance of objects in the perspective view terrain relative to the aircraft without obstructing an operator's view of other information that may be on the same display. The present invention addresses one or more of these needs.